The present disclosure generally relates to a seat belt apparatus or a seat belt retractor that carries out at least one of retracting and withdrawing operations for a seat belt by rotating a spool with an electric motor. More specifically, the disclosure relates to a seat belt apparatus or a seat belt retractor where the electric motor is controlled by an electronic control unit (ECU).
A conventional seat belt apparatus mounted on a motor vehicle (e.g., an automobile) is configured to restrain an occupant with a seat belt so he or she does not leave a seat during an event such as a collision of a motor vehicle, hard braking, etc. The seat belt apparatus includes a seat belt retractor for retracting the seat belt. A conventional seat belt retractor winds the seat belt on a spool when the seat belt is not worn and also allows the seat belt to be withdrawn and worn by the occupant. The seat belt retractor typically includes a locking mechanism that activates during an event to block rotation of the spool in a withdrawing direction so the seat belt cannot be withdrawn and so the occupant is restrained.